Image reading apparatus, default value adjusting method of image reading apparatus, and chart original

ABSTRACT

A lens motor and a conjugate length motor are driven to move a lens unit and a reading section to positions, respectively, which positions corresponding with a set magnification, autofocusing is carried out, and an actual focusing magnification is determined. It is then determined whether the actual focusing magnification is within a standard range corresponding to the set magnification. When the actual focusing magnification is outside the standard range, a number of pulses of the lens motor for changing the actual focusing magnification to the set magnification is calculated, the lens unit is moved again, autofocusing is carried out, and an actual focusing magnification is determined. This movement of the lens unit and autofocusing is carried out repeatedly until the actual focusing magnification falls within the standard range. A default value of resolution of the conjugate length motor is adjusted based on a difference between the pulse numbers for two set magnifications, each pulse number being for when the actual focusing magnification becomes a value within the standard range for the respective set magnification, and on a difference in conjugate length for the two set magnifications. A default value of resolution of the lens motor is adjusted based on a difference between pulse numbers for two set magnifications, each pulse number being for when the actual focusing magnification becomes a value within the standard range for the respective set magnification, and on the difference in distance from a principal point of the lens unit until the focusing position for each of two set magnifications.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image reading apparatus, a defaultvalue adjusting method of an image reading apparatus, and a chartoriginal, and in particular, relates to an image reading apparatushaving default values of a resolution of a pulse motor that moves a lensunit or the like of the image reading apparatus, a default valueadjusting method of an image reading apparatus which adjusts defaultvalues, and a chart original which is directly used in an embodiment ofthe default value adjusting method of an image reading apparatus.

2. Description of the Related Art

Japanese Patent Application Laid-Open (JP-A) No. 5-281631 discloses amethod for adjusting a position of a zoom ring which adjusts themagnification of a zoom lens and a position of a focusing ring whichadjusts the focusing point of the zoom lens, in accordance with the sizeof a photographic print. In this method, a default value of the positionof the zoom ring and a default value of the position of the focusingring, in accordance with the size of a photographic print, are recordedin advance in a memory. On the basis of these default values, theposition of the zoom ring and the position of the focusing ring arecontrolled, an image of a photographic print is image-formed (focused)at an image sensor, and the image thus image-formed at the image sensoris displayed on a preview display apparatus. In cases in which the imagedisplayed on the preview display apparatus is not suitable for thedisplay screen, an operator adjusts the respective positions of the zoomring and the focusing ring such that the image displayed on the previewdisplay apparatus becomes suitable for the display screen, whileobserving the image displayed on the preview display apparatus. Thealready stored default value is changed to the value obtained by theadjustment of the zoom lens. As a result, since an adjusted defaultvalue in accordance with each of the photographic print sizes thereafteris used, it is not necessary to adjust the zoom lens in accordance withthe size of each photographic print. The burden on the operator in termsof time and labor can be reduced.

However, in the conventional adjusting method described above, althoughthe burden on the operator in terms of time and labor is reduced afterthe default value is adjusted, however, during adjustment, much time isrequired, since the default value must be adjusted for each size of thephotographic film while viewing the display screen.

SUMMARY OF THE INVENTION

The present invention has been devised to overcome the above problems.An object of the present invention is to provide an image readingapparatus and a default value adjusting method of an image readingapparatus which reduce the work involved in adjustment. Further, anobject of the present invention is to provide a chart original whichfacilitates detection of positional offset between an original holdingportion and an image reading element.

In order to achieve the above object, the image reading apparatus of thepresent invention comprises:

a reading section movable in an optical axis direction, said readingsection including a lens unit which is movable in the optical axisdirection, and an image reading element which is disposed at a focusingposition of the lens unit and which via the lens unit reads an image ofan original disposed at an original reading position;

first driving means for moving the lens unit in the optical axisdirection in accordance with an inputted signal of a first pulse number;

second driving means for moving the reading section in the optical axisdirection in accordance with an inputted signal of a second pulsenumber;

storing means for storing a first default value, which expresses anamount of movement corresponding to a unit pulse of the first movingmeans, and a second default value, which expresses an amount of movementcorresponding to a unit pulse of the second moving means; and

pulse number calculating means for calculating the first pulse numbercorresponding to a focusing magnification by using the first defaultvalue, inputting a signal of the first pulse number to the first drivingmeans, calculating the second pulse number corresponding to the focusingmagnification by using the second default value, and inputting a signalof the second pulse number to the second driving means.

It is preferable that the image reading apparatus of the presentinvention be provided with adjusting means which makes the pulse numbercalculating means calculate a first pulse number and a second pulsenumber which correspond to a predetermined set focusing magnification,and makes the pulse number calculating means input a signal of the firstpulse number to the first driving means and input a signal of the secondpulse number to the second driving means so that the lens unit and thereading section are moved, and thereafter,

the adjusting means carries out autofocusing, in which the seconddriving means is driven so as to carry out focusing with respect to theoriginal, and carries out magnification adjustment, in which the firstdriving means is driven such that an actual focusing magnification afterautofocusing is carried out coincides with the set focusingmagnification, until the actual focusing magnification becomes a valuewhich is within a standard range with respect to the set focusingmagnification, and

the adjusting means adjusts the second default value on the basis of thesecond pulse number for when the actual focusing magnification becomesthe value within the standard range with respect to the set focusingmagnification and on the basis of a conjugate length for the setfocusing magnification, and adjusts the first default value on the basisof the first pulse number for when the actual focusing magnificationbecomes the value within the standard range with respect to the setfocusing magnification and on the basis of a distance from a principalpoint of the lens unit to the focusing position with respect to the setfocusing magnification.

The adjusting means can adjust the second default value on the basis ofa difference in the second pulse numbers with respect to two setfocusing magnifications, each of the second pulse numbers being for whenthe actual focusing magnification becomes a value within the standardrange for the respective set focusing magnification, and on the basis ofa difference in conjugate lengths for the two set focusingmagnifications, and the adjusting means can adjust the first defaultvalue on the basis of a difference in the first pulse numbers withrespect to the two set focusing magnifications, each of the first pulsenumbers being for when the actual focusing magnification becomes a valuewithin the standard range for the respective set focusing magnification,and on the basis of a difference in distances with respect to the twoset focusing magnifications each of the distances being from theprincipal point of the lens unit to a focusing position.

It is preferable that the image reading apparatus of the presentinvention be provided with positional offset detecting means fordetecting positional offset between the image reading element and anoriginal holding portion which holds the original at the originalreading position, by reading, by using the image reading element, animage of an original located at the original reading position of theoriginal holding portion.

In a default value adjusting method of an image reading apparatus of thepresent invention, the image reading apparatus comprises:

a reading section movable in an optical axis direction, the readingsection including a lens unit which is movable in the optical axisdirection, and an image reading element which is disposed at a focusingposition of the lens unit and which via the lens unit reads an image ofan original disposed at an original reading position;

first driving means for moving the lens unit in the optical axisdirection in accordance with an inputted signal of a first pulse number;

second driving means for moving the reading section in the optical axisdirection in accordance with an inputted signal of a second pulsenumber;

storing means for storing a first default value, which expresses anamount of movement corresponding to a unit pulse of the first movingmeans, and a second default value, which expresses an amount of movementcorresponding to a unit pulse of the second moving means; and

pulse number calculating means for calculating the first pulse numbercorresponding to a focusing magnification by using the first defaultvalue, inputting a signal of the first pulse number to the first drivingmeans, calculating the second pulse number corresponding to the focusingmagnification by using the second default value, and inputting a signalof the second pulse number to the second driving means,

and the default value adjusting method comprising steps of:

making the pulse number calculating means calculate the first pulsenumber and the second pulse number which correspond to a predeterminedset focusing magnification;

making the pulse number calculating means input the signal of the firstpulse number to the first driving means and input the signal of thesecond pulse number to the second driving means so that the lens unitand the reading section are moved;

carrying out autofocusing, in which the second driving means is drivenso as to carry out focusing with respect to the original, and carryingout magnification adjustment, in which the first driving means is drivensuch that an actual focusing magnification after autofocusing is carriedout coincides with the set focusing magnification, until the actualfocusing magnification becomes a value within a standard range withrespect to the set focusing magnification; and

adjusting the second default value on the basis of the second pulsenumber for when the actual focusing magnification becomes the valuewithin the standard range with respect to the set focusing magnificationand on the basis of a conjugate length for the set focusingmagnification, and adjusting the first default value on the basis of thefirst pulse number for when the actual focusing magnification becomesthe value within the standard range with respect to the set focusingmagnification and on the basis of a distance from a principal point ofthe lens unit to the focusing position with respect to the set focusingmagnification.

In the default value adjusting method of the image reading apparatusaccording to claim 7, wherein the second default value is adjusted onthe basis of a difference in the second pulse numbers with respect totwo set focusing magnifications, each of the second pulse numbers beingfor when the actual focusing magnification becomes a value within thestandard range for the respective set focusing magnification, and on thebasis of a difference in conjugate lengths for the two set focusingmagnifications,

and the first default value is adjusted on the basis of a difference infirst pulse numbers with respect to the two set focusing magnifications,each of the first pulse numbers being for when the actual focusingmagnification becomes a value within the standard range for therespective set focusing magnification, and on the basis of a differencein distances with respect to the two set focusing magnifications each ofthe distances being from the principal point of the lens unit to afocusing position.

The chart original of the present invention is a chart original in whichtwo or more patterns are disposed so as to be separated at predeterminedintervals and so as to be symmetric with respect to a second imaginaryline which is orthogonal to a first imaginary line, each of the patternsbeing formed from a first line segment, which is orthogonal to the firstimaginary line, and two second line segments, which are disposed atopposite positions with respect to the first line segment so as tointersect the first line segment, and each of the patterns intersectingthe first imaginary line at the three points.

In the present invention, the first pulse number corresponding to thefocusing magnification is calculated by using the first default value.By inputting a signal of the first pulse number, the lens unit is movedin the optical axis direction by the first moving means. The secondpulse number corresponding to the focusing magnification is calculatedby using the second default value. By inputting a signal of the secondpulse number, the reading section is moved in the optical axis directionby the second moving means. The image of the original, which is disposedat the focusing position of the lens unit and at the original readingposition, is read by the image reading element via the lens unit.

In the present invention, when the default value is adjusted, thedefault value recorded in the storing means are used, the driving meansare driven, and the lens unit and the reading section are thereby movedto positions corresponding to the set focusing magnification determinedin advance. Thereafter, the second driving means is driven so as to befocussed with respect to the original, and the first driving means isdriven such that an actual focusing magnification after autofocusingcoincides with the set focusing magnification, until the actual focusingmagnification becomes a value within a standard range with respect tothe set focusing magnification.

Then, the movement amount corresponding to the unit pulse of the seconddriving means is calculated, based on the second pulse number of whenthe actual focusing magnification becomes a value within the standardrange with respect to the set magnification, and based on the conjugatelength with respect to the set focusing magnification. The seconddefault value recorded in the storing means is changed to the thuscalculated value. Further, the movement amount corresponding to the unitpulse of the first driving means is calculated, based on the first pulsenumber of when the actual focusing magnification becomes a value withinthe standard range with respect to the set magnification, and based onthe distance from the principal point of the lens unit to the focusingposition with respect to the setting focusing magnification. The firstdefault value recorded in the storing means is changed to the thuscalculated value. As a result, the respective planned positions of thelens unit and the reading section for the focusing magnificationcoincides with the respective actual positions.

In the present invention, default values can be adjusted using one setfocusing magnification. However, the default values can be adjusted withfurther accuracy in using two set focusing magnifications, by adjustingthe second default value on the basis of a difference in second pulsenumbers with respect to two set focusing magnifications each of thesecond pulse numbers being for when the actual focusing magnificationbecomes a value within the standard range for the respective setfocusing magnification and on the basis of a difference in conjugatelengths for the two set focusing magnifications, and adjusting the firstdefault value on the basis of a difference in first pulse numbers withrespect to the two set focusing magnifications, each of the first pulsenumbers being for when the actual focusing magnification becomes a valuewithin the standard range for the respective set focusing magnificationand on the basis of a difference in distances with respect to the twoset focusing magnifications each of the distances being from theprincipal point of the lens unit to the focusing position.

In the present invention, it is preferable to provide a positionaloffset detecting means for detecting positional offset between the imagereading element and an original holding portion which holds the originalat the original reading position, by reading, by using the image readingelement, an image of an original located at the original readingposition of the original holding portion.

The positional offset between the original holding portion and the imagereading element can be detected by using the chart original of thepresent invention, in which two or more patterns are disposed so as tobe separated at predetermined intervals and so as to be symmetric withrespect to a second imaginary line which is orthogonal to a firstimaginary line, each of the patterns being formed from a first linesegment, which is orthogonal to the first imaginary line, and two secondline segments, which are disposed at opposite positions with respect tothe first line segment so as to intersect the first line segment, andeach of the patterns intersecting the first imaginary line at the threepoints. The chart original of the present invention is disposed suchthat the first imaginary line is oriented in a direction correspondingto the direction in which the plural pixels of the image reading elementare arrayed. By detecting the intervals between three pointsintersecting the direction in which the pixels are arrayed, thepositional offset between the original holding portion and the imagereading element can be corrected.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exterior view of an image reading apparatus.

FIG. 2 is a cross-sectional front view of an optical system of the imagereading apparatus.

FIG. 3 is a cross-sectional side view of the optical system of the imagereading apparatus.

FIG. 4A is a plan view illustrating an example of a diaphragm.

FIG. 4B is a plan view illustrating an example of a turret.

FIG. 4C is a plan view illustrating an example of an lens diaphragm.

FIG. 4D is a plan view illustrating an example of a CCD shutter.

FIG. 5 is a diagram illustrating main portions of the optical system ofthe image reading apparatus.

FIG. 6 is a block diagram illustrating a schematic structure of anelectrical system of the image reading apparatus.

FIG. 7 is an exterior view of an image reading section of the imagereading apparatus.

FIG. 8 is a flowchart of a routine through which magnificationcalibration is executed in accordance with an embodiment of the presentinvention.

FIG. 9 is a flowchart illustrating details of step S1 in FIG. 8.

FIG. 10 is a flowchart illustrating details of step S2 in FIG. 8.

FIG. 11 is a plan view illustrating a chart pattern.

FIG. 12 is an enlarged view of a chart K of the chart pattern.

FIG. 13 is a plan view illustrating a display screen when results of acompleted magnification calibration are shown.

FIG. 14 is a plan view illustrating a display screen of a read chartpattern and a detected amount of positional offset.

FIGS. 15A through 15F are explanatory diagrams for explaining principlesof detection of an amount of positional offset by using N-shapedpatterns.

FIG. 16 is an exterior view of a carrier mount and jig.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Below, an explanation will be provided of an embodiment of the presentinvention while referring to the Figures.

As illustrated in FIG. 1, a line CCD scanner 14 of an image readingapparatus of the present embodiment is provided with a work table 27having disposed thereon: an image processing section 16 formed with apersonal computer; a mouse 20 connected to the image processing section16; two types of keyboards 12A, 12B connected to the image processingsection 16; and a display 18 connected to the image processing section16.

One of the keyboards, the keyboard 12A, is embedded in a work surface27U of the work table 27. The other keyboard, the keyboard 12B, iscontained within a tray 24 provided at a lower side of the work table27. During use, the keyboard 12B is removed from the tray 24, and isplaced on top of the keyboard 12A. At this time, a cord of the keyboard12B is connected to a jack 110 connected to the image processing section16, and used. During use of the keyboard 12B, data can not be input fromthe keyboard 12A.

A jack of the mouse 20 is inserted into a jack 108 provided at the worktable 27, and is connected to the image processing section 16 via thejack 108. The mouse 20 is stored in a mouse holder 20A when not in use.During use, the mouse 20 is removed from the mouse holder 20A and isplaced on the work surface 27U.

The image processing section 16 is stored inside a storage portion 16Aprovided at a lower side of the work table 27. An open-and-close hatch25 is provided at an aperture portion of the storage portion 16A.Further, by opening the open-and-close hatch 25, the image processingsection 16 can be removed.

The line CCD scanner 14 reads film images recorded on photographic filmsuch as negative film or reversal film. For example, the line CCDscanner 14 can read as objects to be read images recorded on 135-sizephotographic film, 110-size photographic film, photographic film havinga transparent magnetic layer formed thereon (240-size photographic film,i.e., so-called APS film), and 120-size and 220-size (Brownie size)photographic film. The line CCD scanner 14 reads with a line CCD thefilm images of the above-described objects to be read, and outputs imagedata.

The image processing section 16 carries out image processing such asvarious types of corrections or the like of image data input from theline CCD scanner 14, and outputs image data for recording, to an imageoutputting section that records images on printing paper using a laser(not shown).

As shown in FIGS. 2 and 3, an optical system of the line CCD scanner 14is provided with: a light source section 30 disposed at a lower side ofthe work table 27; a diffusion box 40 supported at the work table 27 soas to be replaceable; a film carrier 38 set at the work table 27 so asto be replaceable; and a reading section 43 disposed at a side oppositeto the light source section 30, with the work table 27 therebetween.

The light source section 30 is contained in a metal casing 31. Insidethe casing 31, a lamp 32 comprised of a halogen lamp or a metal halidelamp or the like is disposed.

A reflector 33 is provided at a periphery of the lamp 32, and a portionof light emitted by the lamp 32 is reflected by the reflector 33, in adirection of the reading section 43. A plurality of fans 34 are providedat sides of the reflector 33. The fans 34 operate while the lamp 32 islit, and prevent internal portions of the casing 31 from overheating.

At a light-reflecting side of the reflector 33, the following areprovided, in the following order: an infrared-ray (IR)-cutting filter 35that prevents the temperature of a photographic film 22 from rising bycutting light of wavelengths in the infrared range, thus improvingreading accuracy; a stop 39 (diaphragm) that adjusts the amount of lightfrom the lamp 32 and the amount of the reflected light from thereflector 33; and a turret 36 (see FIG. 4B as well) having fittedtherein a balance filter 36N for negative film and a balance filter 36Pfor reversal film, which appropriately set a color composition of lightreaching the photographic film 22 and the reading section 43, inaccordance with the type of photographic film (negative film/reversalfilm).

The stop 39 is formed with a pair of plates disposed having therebetweenan optical axis L, such that the pair of plates can slide away from ortoward each other. As illustrated in FIG. 4A, each of the pair of platesof the stop 39 has a notch 39A formed at one end thereof, from the oneend of the plate towards the other end along a sliding direction, suchthat the area of the cross-section cut along the direction orthogonal tothe sliding direction continuously changes. The plates are disposed suchthat respective sides of the plates having notch 39A formed therein faceeach other.

In the above-described structure, in order to ensure light of apredetermined color composition, one of the filter 36N and the filter36P is positioned on the optical axis L in accordance with the type ofphotographic film, and light to be transmitted through the stop 39 isadjusted to predetermined amounts by the position of the stop 39.

The diffusion box 40 is formed such that towards upper portions thereof,namely, as the photographic film 22 is approached, a dimension of thediffusion box 40 decreases in the direction the photographic film 22,which is conveyed by the film carrier 38, is conveyed (see FIG. 2). Adimension of the diffusion box 40 increases (see FIG. 3) in thedirection orthogonal to the direction the photographic film 22 isconveyed (i.e., in the direction of the width of the photographic film22). The film carrier 38 is attached to a carrier mount 41. Further, alight diffusing plate (not illustrated) is attached to the diffusion box40 at a light exiting side thereof. Although the diffusion box 40 is for135-size photographic film, diffusion boxes (not shown) are prepared forphotographic film of other sizes, and are used by carrying outreplacement in accordance with the size of a photographic film.

Towards the film carrier 38 (namely, towards the photographic film 22),light entering the diffusion box 40 becomes slit light having alongitudinal direction in the transverse direction of the photographicfilm, and exits the diffusion box 40 having been diffused by the lightdiffusing plate. In this way, due to the fact that light exiting thediffusion box 40 is diffused, unevenness in the amount of lightilluminated onto the photographic film 22 is decreased. As a uniformamount of slit light is illuminated onto the film image, even ifscratches are present on the film image, the scratches are not obvious.

A film carrier 38 and a diffusion box 40 are prepared for each type ofthe photographic film 22, are selected in accordance with thephotographic film 22, and mounted on the carrier mount 41. Details ofthe carrier mount 41 are shown in FIG. 16.

At each of respective positions in a top and bottom surface of the filmcarrier 38 that correspond to the optical axis L, a long and narrowaperture (not illustrated) is provided in the transverse direction ofthe photographic film 22, such that the length of the aperture is longerthan the width of the photographic film 22. The slit light from thediffusion box 40 is illuminated onto the photographic film 22 via theaperture provided at the bottom surface of the film carrier 38, and istransmitted through the photographic film 22 to be illuminated onto thereading section 43 via the aperture provided at the top surface of thefilm carrier 38.

Further, a guide (not shown) is formed at the film carrier 38, the guideguiding by curving the photographic film 22 such that a region along thetransverse direction of the photographic film in a position (readingposition) illuminated by the light in the form of a slit from thediffusion box 40 becomes linearly indented or recessed. As a result, itis ensured that the photographic film 22 is a flat plane at the readingposition.

Further, the diffusion box 40 is supported so that the top surfacethereof is proximal to the reading position. A notch portion throughwhich the diffusion box 40 can enter is provided at the bottom surfaceof the film carrier 38, so that the film carrier 38 and the diffusionbox 40 do not interfere with each other when the film carrier 38 isloaded.

Further, the film carrier conveys a photographic film at a first speedduring pre-scanning, and conveys the photographic film at a secondspeed, which is slower than the first speed, during fine-scanning. As aresult, resolution during fine-scanning is better than resolution duringpre-scanning. Density and size and the like of each of the film imagesis detected with data obtained during pre-scanning, and based on suchdata, reading conditions during fine-scanning, namely, conditionsdetermining the light amount to be illuminated onto the film and theduration of charge storage of the CCD are computed. While thephotographic film is conveyed at the fixed second speed duringfine-scanning, the stop 39 is controlled so that in accordance with thereading conditions, an amount of light corresponding to the density ofthe film image is illuminated, and the duration of charge storage of theCCD is controlled.

The image reading section 43 is disposed so as to be contained inside acasing 44. A loading stand 47 is provided at an internal portion of thecasing 44, the loading stand 47 having a line CCD 116 attached to anupper surface thereof.

As shown in FIG. 7, an external cylinder 49A is fixed at the loadingstand 47, the external cylinder 49A forming a lens-barrel 49 and havingcut thereinto two long apertures 49C, which extend in a direction of aline parallel to the optical axis L and which face each other. Insidethe external cylinder 49A, an internal cylinder 49B is disposed so as tobe rotatable. The internal cylinder 49B has cut thereinto twospiral-shaped long apertures 49D, which face each other. A ring-shapedgear 49E is fixed at an outer periphery end portion of the internalcylinder 49B at the loading stand 47 side. This gear 49E meshes with agear fixed at a rotational axis of a lens motor 60, via a series ofgears.

Two rods 50A are fixed at a lens unit 50, so as to face each other. Thelens unit 50 has a focal distance f_(j). Each of these rods 50A isinserted so as to pass through the respective long aperture 49D and 49C.

Accordingly, when the lens motor 60 is driven to rotate, the internalcylinder 49B rotates, and the rods 50A move along the long apertures49C, due to the spiral-shaped long apertures 49D. As a result, the lensunit 50 is slid in a direction of the optical axis L, namely, in thedirections of arrow A, so as to near or move away from the work table27, for adjusting the magnification (e.g., reduction, enlargement).

A support frame 45 is arranged in a standing condition at the work table27. The reading section 43 is meshed with a guide rail 42 which isattached to this support frame 45 and is provided with a ball screw. Thereading section 43 is supported so as to be slidable in the directionsof arrow B so as to move toward and away from the work table 27 alongthe guide rail 42, by driving a conjugate length motor 58 which hasmeshed with the guide rail 42. This reading section 43 is moved duringautofocusing, when the conjugate length is adjusted. The lens unit 50 iscomprised of plural lenses, and an aperture 51 (lens diaphragm) isprovided between the plural lenses.

As indicated in FIG. 4C, the aperture stop 51 is provided with aplurality of stop plates 51A (diaphragm plates), which are each formedin a substantially C-shaped configuration. The stop plates 51A aredisposed evenly around the periphery of the optical axis L. An endportion of each of the stop plates 51A is axially supported so as to berotatable about a pin. When driving force from an aperture stop drivingmotor (to be described later) is transmitted thereto, each of the stopplates 51A rotate in the same direction. Together with this rotation ofthe stop plates 51A, the area of a portion (the substantiallystar-shaped portion in FIG. 4C), which is not cut off from light by thestop plates 51A and which has as the center the optical axis, changes.As a result, the amount of light that passes through the aperture stop51 changes.

In the line CCD 116, sensing portions are provided, at which aredisposed: a plurality of CCD cells provided in a line along thetransverse direction of the photographic film 22, which CCD cells arestructured by photoelectric converting elements such as photodiodes orthe like; and electronic shutter mechanisms. These sensing portions areprovided in three parallel lines spaced apart from each other, and acolor separating filter of R, G, or B is mounted to the light-incidentside of each of the sensing portions. Namely, the line CCD 116 is a3-line color CCD formed with a R-line sensor, a G-line sensor, and aB-line sensor. Further, plural transmitting portions are provided invicinities of each of the sensing portions so as to correspond to thesensing portions. The charge accumulated in each CCD cell of the sensingportions is transmitted sequentially via the corresponding transmittingportion.

A CCD shutter 52 is provided at the light-incident side of the line CCD116. As illustrated in FIG. 4D, an ND filter 52ND is fitted into the CCDshutter 52. The CCD shutter 52, which rotates in the direction of arrowu, switches to one of: a completely closed state (a portion 52B or thelike, where the ND filter 52ND is not fitted, is positioned at aposition 52C, which contains the optical axis L), in which the CCDshutter 52 blocks light which would otherwise be incident on the lineCCD 116 for dark correction; a completely open state (the position ofFIG. 4D), in which the CCD shutter 52 allows light to be incident ontothe line CCD 116 for regular reading and for light correction and; and areduced light state (the ND filter 52ND is positioned at the position52C), in which the light to be incident on the line CCD 116 is reducedby the ND filter 52ND for linearity correction.

A compressor 94, which generates cooling air to cool the photographicfilm 22, is provided at the work table 27, as illustrated in FIG. 3. Thecooling air generated by the compressor 94 is supplied to a readingposition (not illustrated) of the film carrier 38, via a guide duct 95.As a result, a region including the reading position for thephotographic film 22 can be cooled. Further, a flow rate sensor 96, fordetecting the flow rate of the cooling air, is attached to the guidepipe 95.

Further, as illustrated in FIG. 5, a reading section starting pointsensor 59, for detecting the starting point position of the readingsection 43, is attached at the vicinity of the guide rail 42. A lensstarting point sensor 61, for detecting the starting point position ofthe lens unit 50, is attached at the lens-barrel 49.

Next, while referring to main portions of the optical system of the lineCCD scanner 14 illustrated in FIG. 5, the schematic structure of theelectric system of the line CCD scanner 14 and the image processingsection 16 will be explained.

The line CCD scanner 14 has a microprocessor 46 which governs theoverall control of the line CCD scanner 14. A RAM 68 (e.g., an SRAM) anda ROM 70 (e.g., a ROM whose stored contents are rewritable) areconnected to the microprocessor 46 via a bus 66. A lamp driver 53, thecompressor 94, the flow rate sensor 96, and a motor driver 48 areconnected to the microprocessor 46. The lamp driver 53 turns the lamp 32on and off in accordance with instructions from the microprocessor 46.

When a film image of the photographic film 22 is being read, themicroprocessor 46 operates the compressor 94 to supply cooling air tothe photographic film 22. The flow rate of the cooling air is detectedby the flow rate sensor 96, and the microprocessor 46 sensesabnormalities.

A turret driving motor 54 and a turret position sensor 55 (see FIG. 4B)are connected to the motor driver 48. The turret driving motor 54 drivesthe turret 36 to rotate in the direction of arrow t of FIG. 4B such thateither of the balance filter 36N for negative films or the balancefilter 36P for reversal films of the turret 36 is positioned on theoptical axis L. The turret position sensor 55 detects a referenceposition (an unillustrated notched portion) of the turret 36. Alsoconnected to the motor driver 48 are a stop driving motor 56 for slidingthe stop 39, a stop position sensor 57 which detects the position of thestop 39, a conjugate length motor 58 which comprises a step motor andwhich slides the reading section 43 (i.e., the line CCD 116 and the lensunit 50) along the guide rail 42, the reading section starting pointsensor 59 for detecting the starting position (origin) of the readingsection 43, the lens motor 60 which comprises a step motor and whichslides the lens unit 50 along the optical axis L, the lens positionstarting point (origin) sensor 61 for detecting the starting pointposition of the lens unit 50, an aperture stop driving motor 62 forrotating the stop plates 51A of the aperture stop 51, an aperture stopposition sensor 63 for detecting the position of the aperture stop 51(the positions of the stop plates 51A), a shutter driving motor 64 forswitching the CCD shutter 52 to one of the completely closed state, thecompletely open state, and the reduced-light state, a shutter positionsensor 65 for detecting the position of the shutter, and a fan drivingmotor 37 for driving the fans 34.

When pre-scanning (preliminary reading) and fine scanning (actualreading) are carried out by the line CCD 116, on the basis of thepositions of the turret 36 and the stop 39 respectively detected by theturret position sensor 55 and the stop position sensor 57, themicroprocessor 46 rotates the turret 36 by the turret driving motor 54and slides the stop 39 by the stop driving motor 56 so as to adjust thelight illuminated onto the film image.

The microprocessor 46 determines the focusing magnification inaccordance with the size of the film image, whether trimming is to becarried out, and the like. The microprocessor 46 slides the readingsection 43 by the lens motor 60 on the basis of the starting point ofthe lens unit, which is detected by the lens starting point sensor 61,so that the film image is read by the line CCD 116 at the determinedfocusing magnification. Further, the microprocessor 46 slides thereading section 43 by the conjugate length motor 58 on the basis of theposition of the reading section 43, which is detected by the readingsection starting point sensor 59, to carry out autofocusing.

When carrying out focusing control to make the light-receiving surfaceof the line CCD 116 coincide with the film image focusing position bythe lens unit 50 (i.e., when autofocusing control is carried out), themicroprocessor 46 slides only the reading section 43 by the conjugatelength motor 58. This focusing control can be carried out such that, forexample, the contrast of the film image read by the line CCD 116 is amaximum (what is known as the image contrast method). Alternatively, adistance sensor which measures by infrared rays or the like the distancebetween the photographic film 22 and the lens unit 50 (or the line CCD116) may be provided, and focusing control can be carried out on thebasis of the distance detected by the distance sensor instead of on thebasis of the data of the film image.

A timing generator 74 is connected to the line CCD 116. The timinggenerator 74 generates various types of timing signals (clock signals)for operating the line CCD 116, an A/D converter 82 (which will bedescribed later) and the like. The signal output terminal of the lineCCD 116 is connected to the A/D converter 82 by an amplifier 76. Thesignal outputted from the line CCD 116 is amplified by the amplifier 76and is converted into digital data at the A/D converter 82.

The output terminal of the A/D converter 82 is connected to the imageprocessing section 16 via a correlation double sampling circuit (CDS) 88and an interface (I/F) circuit 90 in that order. At the CDS 88,feedthrough data which expresses the level of a feedthrough signal andpixel data expressing the level of a pixel signal are respectivelysampled, and the feedthrough data is subtracted from the pixel data foreach pixel. The results of calculation (pixel data which accuratelycorresponds to the amount of accumulated charge in each CCD cell) areoutput successively to the image processing section 16 via the I/Fcircuit 90 as scan image data.

Because the R, G, B photometric signals are outputted in parallel fromthe line CCD 116, three signal processing systems, each having anamplifier 76, an A/D converter 82 and a CDS 88, are provided. The R, G,B image data which is the scan image data are inputted in parallel fromthe I/F circuit 90 to the image processing section 16.

Further, the image processing section 16 is connected to the display 18,the keyboards 12A, 12B, the mouse 20 and the film carrier 38.

Formula (1) and formula (2) given below are for calculating each of thenumber of driving pulses KSP_(m) for the conjugate length motor 58 andthe number of driving pulses LSP_(m) for the lens motor 60 in accordancewith each of the setting magnifications m (for example, 0.7,1.0,1.5 andthe like). Formula (1) and formula (2) are recorded in the ROM 70 of theimage reading apparatus, in which reading and writing is possible beforeshipment from the factory. Further, default values KSB, LSB of which arethe respective resolutions of the motors (the distance that can be movedwith one pulse) are recorded in advance in the ROM 70. Further, thesetting magnification m can be set as a different value in accordancewith the film size, such as 135-size, APS, Brownie and the like.

KSP _(m)=(K _(m) −K _(o))/KSB−KGO  (1)

Here, K_(o) is the conjugate length of the lens unit 50, which has afocal distance f_(j), when the reading section is positioned at thestarting point (origin); KGO is the number of pulses (number of startingpoint offset pulses) for when the reading section is positioned at thestarting point; KSB is the default value of the resolution of theconjugate length motor 58; and K_(m) is the conjugate length of the lensunit when the setting magnification m is as represented by the followingformula (1-1).

K _(m)=(1+m)² ·f _(j) /m  (1-1)

LSP _(m)=(b _(o) −b _(m))/LSB−LGO  (2)

Here, b_(o) is the distance from the principal point of the lens whenthe lens unit is positioned at the starting point to the light-receivingsurface of the line CCD; LGO is the number of pulses (number of startingpoint offset pulses) when the lens unit is positioned at the startingpoint; LSB is the default value of the resolution of the lens motor 60;b_(m) is the distance from the principal point of the lens unit to thelight receiving surface of the CCD when the setting magnification m isas represented by the following formula.

b _(m)=(1+m)·f _(j)  (2-2)

Further, the focal distance f_(j) when the temperature of the lens unitis T° C. can be calculated by the following formula, where f_(o) is thefocal distance at a reference temperature T_(o) (for example, 20° C.),and k is the variable coefficient of the focal distance (for example,0.004).

f _(j) =f _(o) +k(T−T _(o))

Next, calibration of the optical magnification of the present embodimentwill be explained. This calibration is carried out when the imagereading apparatus is shipped out. As a result of this calibration, theactual focusing magnification is made to coincide with the plannedvalue, and an error in mechanical attachment is canceled by an offset ofsetting pulses, thereby correcting moving resolution in the direction ofthe optical axis.

The calibration of the optical magnification is carried outautomatically after optical axis adjustment for making the optical axisof the optical system coincide with the center of the line CCD, andafter reading position adjustment for adjusting the position of thecarrier mount 41 such that the position of the film carrier 38 which isthe original holding portion coincides with the line CCD position. Theamount of positional offset of the carrier mount 41 from the line CCD isdetected by the line CCD reading an image of a chart original 72, whichis disposed at the original reading position, using a jig 71 having thechart original 72 held at a surface thereof, as shown in FIG. 16. Thereading position adjustment is carried out in accordance with thedetected amount of positional offset. Further, the chart original 72 isformed by a glass plate, with a chart pattern recorded thereon. Thechart pattern is recorded on the glass plate by carrying out etchingthereon.

First, the chart pattern used in the detection of the amount ofpositional offset will be described. As illustrated in FIG. 11, in thechart pattern used in the present embodiment, a plurality of patternsare formed symmetrically at the left and the right of a pattern Gpositioned at the center. (In the present embodiment, there are 13patterns A through M.) In FIG. 11, the dashed line represents a firstimaginary line VL which corresponds to the direction in which the lineCCD cells are arrayed (the CCD line direction) when the chart original72 is set at the original reading position. The patterns F and H, thepatterns E and I, the patterns D and J, the patterns C and K, thepatterns B and L, and the patterns A and M are disposed so as to bespaced apart at predetermined distances symmetrically with respect to acentral line CL which forms a part of the pattern G.

As illustrated in FIG. 12, the patterns C, D, E, I, J, K (hereinafterreferred to as the “N-shaped patterns”) are formed from a first linesegment which is perpendicular to the imaginary line VL, and two secondline segments which intersect the first line segment at 45° at the endportions of the first line segment and are oriented in respectivelyopposite directions with respect to the first line segment. The N-shapedpattern and the imaginary line VL intersect at three points α₀, β₀, andγ₀. The distance between α₀ and β₀ and the distance between β₀ and γ₀are equal.

Next, the method of detecting the positional offset by using the jig 71having the chart original 72 held at the surface thereof will bedescribed.

When the optical axis adjustment of the optical system and the line CCDis completed, the jig 71 having the chart original 72 held at thesurface thereof is made to abut against the standard abutting surface ofthe carrier mount 41 so as to be set on the carrier mount 41. The chartpattern of the chart original 72 is read by the line CCD. Because thefilm is conveyed perpendicularly to the line CCD, the conveyingdirection will be called the left-and-right direction and the CCD linedirection will be called the front-and-back direction. The jig 71, whichhas the chart original 72 held at the surface thereof, is set such thatthe CCD line direction, i.e., the front-and-back-direction, is thelongitudinal direction of the chart pattern (the direction of the firstimaginary line).

As illustrated in FIG. 14, the read chart pattern is displayed on adisplay 18. The amount of positional offset, which expresses by how muchthe imaginary line VL of the chart pattern is offset from the CCD linedirection, is detected, and is displayed on the screen together with theread chart pattern.

For example, the amount of positional offset of the imaginary line VL inthe front-and-back direction (i.e., the offset of the center line of thepattern G from the optical axis) is detected by using the pattern G, anda display such as “front/back ###” is effected. Further, for example, byusing pattern C and pattern K which are a pair of symmetrically disposedN-shaped patterns, the amount of positional offset, in theleft-and-right direction, of the imaginary line VL with respect to theCCD line direction, and the amount of positional offset, in therotational direction around the optical axis, of the imaginary line VLwith respect to the CCD line direction are detected, and a display suchas “left/right ###” is effected.

Here, the principles of detection of the amount of positional offsetusing a pair of symmetrically disposed N-shaped patterns will be brieflyexplained. FIG. 15A is a projected image of the pattern E and thepattern I in a case in which the carrier mount 41 is at the properreading position and the imaginary line VL coincides with the CCD linedirection. The display pattern shown on the display at this time isschematically illustrated in FIG. 15B. The points of intersection of therespective patterns with the CCD line direction are α, β, and γ, and foreach pattern, the distance between α and β and the distance between βand γ are equal. Further, the distance between α and β at pattern E andat pattern I are equal, and the distance between β and γ at pattern Eand at pattern I are equal.

If the carrier mount 41 is offset toward the right from the properreading position, the CCD line direction is offset toward the left withrespect to the chart original 72 which is held at the jig 71. Asillustrated in FIG. 15D, in accordance with the amount of offset of theCCD line direction, the distance between α and β increases and thedistance between β and γ decreases. Conversely, if the carrier mount 41is offset toward the left from the proper reading position, the CCD linedirection is offset toward the right. As illustrated in FIG. 15C, inaccordance with the amount of offset of the CCD line direction, thedistance between α and β decreases and the distance between β and γincreases. Accordingly, the amount of offset of the carrier mount 41 inthe left-and-right direction can be calculated from the ratio of thedistance between α and β and the distance between β and γ.

If the carrier mount 41 is rotated toward the right from the properreading position, the CCD line direction is rotated toward the left. Asillustrated in FIG. 15E, at pattern E, the distance between α and βdecreases and the distance between β and γ increases in accordance withthe amount of rotation of the CCD line direction, whereas at pattern I,the distance between α and β increases and the distance between β and γdecreases in accordance with the amount of rotation of the CCD linedirection. Conversely, if the carrier mount 41 is rotated toward theleft from the proper reading position, the CCD line direction is rotatedtoward the right. As illustrated in FIG. 15E, at pattern E, the distancebetween α and β increases and the distance between β and γ decreases inaccordance with the amount of rotation of the CCD line direction,whereas at pattern I, the distance between α and β decreases and thedistance between β and γ increases in accordance with the amount ofrotation of the CCD line direction. Accordingly, the amount of offset ofthe carrier mount 41 in the rotational direction can be calculated fromthe ratio of the distance between α and β and the distance between β andγ at pattern E, and from the ratio of the distance between α and β andthe distance between β and γ at pattern I.

The adjustment of the reading position is carried out in accordance withthe detected amount of positional offset of the imaginary line VL fromthe CCD line direction. For example, if it is displayed that theimaginary line VL is offset ## toward the right, the carrier mount 41 ismoved by an amount corresponding to ## in the right direction. If it isdisplayed that the imaginary line VL is offset #### in a right rotation,the carrier mount 41 is moved by an amount corresponding to #### in aright rotation. The adjustment of the reading position may be carriedout manually or automatically. The carrier mount 41 can be moved bymoving the jig 71.

As described above, after the optical axis adjustment and readingposition adjustment have been carried out, the imaginary line VLcoincides with the array direction of the line CCD passing through theoptical axis, and the central line CL passes through the optical axis.

Next, by again using the jig 71, at which the chart original 72 is heldat the surface thereof, the chart patterns as shown in FIG. 11 beingrecorded on the chart original 72, as illustrated in FIG. 8, calibrationfor the setting magnification ml (for example, 0.7 times) is effected instep S1, and thereafter, calibration for the setting magnification m2(for example, 1.0 times) is effected in step S2.

First, calibration for the magnification ml will be explained withreference to FIG. 9. In step S11, the number of setting pulses of theconjugate length motor 58 and the number of setting pulses of the lensmotor 60, which are for the magnification ml, are calculated using theformulas (1) and (2) and the default values KSB, LSB recorded in the ROM70. By driving the motors 58, 60 by the numbers of setting pulses, thelens unit and the reading section are moved to the setting positions.

In step S12, the conjugate length motor is driven so as to focus on thechart pattern based on the output of the G-line sensor, therebyexecuting autofocusing (AF). In step S13, the number of pulses when thefocusing to the chart pattern is done is recorded in the RAM as thenumber of pulses KSP_(AF) of the conjugate length motor and the numberof pulses LSP_(AF) of the lens motor, which are both of after completionof autofocusing. During execution of autofocusing, the lens motor 60 isstopped.

In step S14, position coordinates β_(K) and β_(C), which are at therespective centers of patterns C and K of FIG. 11, are calculated basedon output of the G-line sensor, and in step S15, the actual focusingmagnification JM_(m1) for the G-line sensor is calculated. As shown inFIG. 12, center coordinates can be represented by the intersection ofthe horizontal line and a vertical line of the pattern.

JM _(m1)=(β_(K)−β_(C))/BN  (3)

Here, BN is the actual distance between the charts C and K.

Subsequently, in step S16, it is determined whether the actual focusingmagnification JM_(m1) is outside a standard range, by determiningwhether the actual focusing magnification JM_(m1) is a value outside apredetermined range on the basis of as a standard the magnification m1.

In cases where the actual focusing magnification JM_(m1) is within thestandard range: in step S17, the number of pulses KSP_(AF) of aftercompletion of autofocusing is stored as the number of control pulsesKP_(m1) of the conjugate length motor, and the number of pulses LSP_(AF)is stored as the number of control pulses LP_(m1) of the lens motor withrespect to magnification m1.

On the other hand, in cases where the actual focusing magnificationJM_(m1) is determined to be outside the standard range in step S16: instep S18, for the actual focusing magnification JM_(m1), the distanceb_(JMm1) (position of the lens principal point), which is from theprincipal point of the lens to the light-receiving surface of the lineCCD, is calculated. This distance b_(JMm1) is determined in thefollowing way, using the above formulas (1-1) and (2-2).

 b _(JMm1) =JM _(m1) ·K _(JMm1)/(1+JM _(m1))  (4)

Note, K_(JMm1)=(1+JM_(m1))²·f_(j)/JM_(m1)

Subsequently, in step S19, the offset pulses LOP of the lens motor iscalculated as follows: the difference between the distance b_(JMm1) forthe actual focusing magnification, which distance is from the principalpoint of the lens to the light-receiving surface of the line CCD, andthe distance b_(m1) for the magnification m1, which distance is from theprincipal point of the lens to the light-receiving surface of the lineCCD, is divided by the resolution of the lens motor, as indicated in thefollowing formula.

LOP=(b _(JMm1) −b _(m1))/LSB  (5)

Subsequently, in step S20, the number of setting pulses LSPM, of thelens motor for the magnification ml and the offset pulse LOP are addedtogether in order to reset the driving pulses of the lens motor(=LSP_(m1)+LOP), and the lens unit is moved. Thereafter, the processreturns to step S12, the conjugate length motor is driven andautofocusing is effected again. Steps S12 to S16 are repeatedly executeduntil it is determined that the actual focusing magnification JM_(m1)falls within the standard range in step S16. As a result, the positionof the lens unit can be controlled so that the actual focusingmagnification of after autofocusing coincides with the settingmagnification.

In cases where the actual focusing magnification JM_(m1) falls withinthe standard range: as described above, in step S17, the number ofpulses KSP_(AF) of after completion of autofocusing is stored as thenumber of control pulses KP_(m1) of the conjugate length motor, and thenumber of pulses LSP_(AF) is stored as the number of control pulsesLP_(m1) of the lens motor with respect to magnification m1.

Subsequently, calibration for the setting magnification m2 will bedescribed with reference to FIG. 10. In FIG. 10, the magnification ischanged from ml (of FIG. 9) to m2, and position coordinates β_(D) andβ_(J), which are the respective centers of patterns D and J, are used tocalculate the actual focusing magnification. In other respects, theexplanation is the same as that given above for FIG. 9, and so furtherexplanation thereof will be omitted.

In step S3 of FIG. 8, the resolution KJB of the conjugate length motorand the resolution LJB of the lens motor are calculated in accordancewith the following formulas, using the difference in the conjugatelength between different setting magnifications and the difference inthe number of actual measurement pulses between differentmagnifications.

KJB=(K _(m1) −K _(m2))/KP _(m1) −KP _(m2))  (6)

LJB=(b _(m2) −b _(m1))/(LP _(m2) −LP _(m1))  (7)

In step S4, the default value KSB of the conjugate length motor ischanged to the default value KJB, which is shown in formula (6)calculated as above. In addition, the default value LSB of the lensmotor is changed to the default value LJB, which is shown in formula (7)calculated as above. The calibration that is executed in this way isdisplayed on the display as calibration results, as illustrated in FIG.13. Further each of the “#” which appears in FIG. 13 representsnumerical values.

Further, the number of setting pulses of after completion ofmagnification calibration is obtained by the following formulas. Inaccordance with the following formulas, the number of setting pulses foreach of the magnifications is calculated, to govern thereby theconjugate length motor and the lens motor.

conjugate length motor

KP _(m)=((1+m)² ·f _(j) /m−K _(o))/KJB−KGO  (8)

lens motor

LP _(m)=(b _(o)−(1+m)·f _(j))/LJB−LGO  (9)

Above, an example was described in which the default values are adjustedusing two setting magnifications. However, instead, the default valuesmay be adjusted using one setting magnification.

When the above-described adjustment is finished, the jig 71 is removedfrom the carrier mount 41, and adjustment is completed.

Next, a description will be given of a case in which the operatoradjusts the print magnification using the above-described image readingapparatus. In the ROM of the image reading apparatus, an electronmagnification default value for adjusting the print magnification inaccordance with the film size and the print size is recorded. The printmagnification is defined as the product of the optical magnification mand the electron magnification, and the print magnification is changedby changing the electron magnification without changing the opticalmagnification. This electron magnification changes the magnification ofthe image displayed by enlarging or reducing the image pixels based onimage processing.

The image data of the film read by the line CCD is stored in the RAM.Film images based on the image data stored in the RAM are displayed inthe display 18. In cases in which the print magnification is adjusted,the operator inputs an adjustment value via the keyboard while viewingthe displayed image. As a result, together with the change in the sizeof the display screen in accordance with the adjustment value, thedefault value of the electron magnification changes in accordance withthe adjustment value. After the default value is adjusted, an imagecorresponding to the print magnification corresponding to the adjusteddefault value is displayed on the display 18.

As described above, in accordance with the present invention, an imagereading apparatus and a default value adjusting method of an imagereading apparatus which reduce the work involved in adjustment areprovided. Further, a chart original which facilitates detection ofpositional offset between an original holding portion and an imagereading element is provided.

What is claimed is:
 1. An image reading apparatus comprising: a reading section movable in an optical axis direction, said reading section including a lens unit which is movable in the optical axis direction, and an image reading element which is disposed at a focusing position of the lens unit and which via the lens unit reads an image of an original disposed at an original reading position; first driving means for moving the lens unit in the optical axis direction in accordance with an inputted signal of a first pulse number; second driving means for moving said reading section in the optical axis direction in accordance with an inputted signal of a second pulse number; storing means for storing a first default value, which expresses an amount of movement corresponding to a unit pulse of said first moving means, and a second default value, which expresses an amount of movement corresponding to a unit pulse of said second moving means; and pulse number calculating means for calculating the first pulse number corresponding to a focusing magnification by using the first default value, inputting a signal of the first pulse number to said first driving means, calculating the second pulse number corresponding to the focusing magnification by using the second default value, and inputting a signal of the second pulse number to said second driving means.
 2. An image reading apparatus according to claim 1, further comprising: adjusting means which makes said pulse number calculating means calculate a first pulse number and a second pulse number which correspond to a predetermined set focusing magnification, and makes said pulse number calculating means input a signal of the first pulse number to said first driving means and input a signal of the second pulse number to said second driving means so that the lens unit and said reading section are moved, and thereafter, said adjusting means carries out autofocusing, in which said second driving means is driven so as to carry out focusing with respect to the original, and carries out magnification adjustment, in which said first driving means is driven such that an actual focusing magnification after autofocusing is carried out coincides with the set focusing magnification, until the actual focusing magnification becomes a value which is within a standard range with respect to the set focusing magnification, and said adjusting means adjusts the second default value on the basis of the second pulse number for when the actual focusing magnification becomes the value within the standard range with respect to the set focusing magnification and on the basis of a conjugate length for the set focusing magnification, and adjusts the first default value on the basis of the first pulse number for when the actual focusing magnification becomes the value within the standard range with respect to the set focusing magnification and on the basis of a distance from a principal point of the lens unit to the focusing position with respect to the set focusing magnification.
 3. An image reading apparatus according to claim 2, wherein said adjusting means adjusts the second default value on the basis of a difference in the second pulse numbers with respect to two set focusing magnifications, each of the second pulse numbers being for when the actual focusing magnification becomes a value within the standard range for the respective set focusing magnification, and on the basis of a difference in conjugate lengths for the two set focusing magnifications, and said adjusting means adjusts the first default value on the basis of a difference in the first pulse numbers with respect to the two set focusing magnifications, each of the first pulse numbers being for when the actual focusing magnification becomes a value within the standard range for the respective set focusing magnification, and on the basis of a difference in distances with respect to the two set focusing magnifications each of the distances being from the principal point of the lens unit to a focusing position.
 4. An image reading device apparatus according to claim 3, further comprising: positional offset detecting means for detecting positional offset between the image reading element and an original holding portion which holds the original at the original reading position, by reading, by using the image reading element, an image of an original located at the original reading position of the original holding portion.
 5. An image reading device apparatus according to claim 2, further comprising: positional offset detecting means for detecting positional offset between the image reading element and an original holding portion which holds the original at the original reading position, by reading, by using the image reading element, an image of an original located at the original reading position of the original holding portion.
 6. An image reading device apparatus according to claim 1, further comprising: positional offset detecting means for detecting positional offset between the image reading element and an original holding portion which holds the original at the original reading position, by reading, by using the image reading element, an image of an original located at the original reading position of the original holding portion.
 7. A default value adjusting method of an image reading apparatus in which default values of the image reading apparatus are adjusted, the image reading apparatus comprising: a reading section movable in an optical axis direction, said reading section including a lens unit which is movable in the optical axis direction, and an image reading element which is disposed at a focusing position of the lens unit and which via the lens unit reads an image of an original disposed at an original reading position; first driving means for moving the lens unit in the optical axis direction in accordance with an inputted signal of a first pulse number; second driving means for moving said reading section in the optical axis direction in accordance with an inputted signal of a second pulse number; storing means for storing a first default value, which expresses an amount of movement corresponding to a unit pulse of said first moving means, and a second default value, which expresses an amount of movement corresponding to a unit pulse of said second moving means; and pulse number calculating means for calculating the first pulse number corresponding to a focusing magnification by using the first default value, inputting a signal of the first pulse number to said first driving means, calculating the second pulse number corresponding to the focusing magnification by using the second default value, and inputting a signal of the second pulse number to said second driving means, and the default value adjusting method comprising steps of: making said pulse number calculating means calculate the first pulse number and the second pulse number which correspond to a predetermined set focusing magnification; making said pulse number calculating means input the signal of the first pulse number to said first driving means and input the signal of the second pulse number to said second driving means so that the lens unit and said reading section are moved; carrying out autofocusing, in which said second driving means is driven so as to carry out focusing with respect to the original, and carrying out magnification adjustment, in which said first driving means is driven such that an actual focusing magnification after autofocusing is carried out coincides with the set focusing magnification, until the actual focusing magnification becomes a value within a standard range with respect to the set focusing magnification; and adjusting the second default value on the basis of the second pulse number for when the actual focusing magnification becomes the value within the standard range with respect to the set focusing magnification and on the basis of a conjugate length for the set focusing magnification, and adjusting the first default value on the basis of the first pulse number for when the actual focusing magnification becomes the value within the standard range with respect to the set focusing magnification and on the basis of a distance from a principal point of the lens unit to the focusing position with respect to the set focusing magnification.
 8. A default value adjusting method of the image reading apparatus according to claim 7, wherein the second default value is adjusted on the basis of a difference in the second pulse numbers with respect to two set focusing magnifications, each of the second pulse numbers being for when the actual focusing magnification becomes a value within the standard range for the respective set focusing magnification, and on the basis of a difference in conjugate lengths for the two set focusing magnifications, and the first default value is adjusted on the basis of a difference in first pulse numbers with respect to the two set focusing magnifications, each of the first pulse numbers being for when the actual focusing magnification becomes a value within the standard range for the respective set focusing magnification, and on the basis of a difference in distances with respect to the two set focusing magnifications each of the distances being from the principal point of the lens unit to a focusing position.
 9. A default value adjusting method of the image reading apparatus according to claim 8, wherein a positional offset between the image reading element and an original holding portion which holds the original at the original reading position is detected, by reading, by using the image reading element, an image of an original located at the original reading position of the original holding portion.
 10. A default value adjusting method of the image reading apparatus according to claim 7, wherein a positional offset between the image reading element and an original holding portion which holds the original at the original reading position is detected, by reading, by using the image reading element, an image of an original located at the original reading position of the original holding portion. 